Extraluminal laryngotracheal fixation with absorbable miniplates

Preclinical assessment of resorbable silk splints for the treatment of pediatric tracheomalacia

OBJECTIVE

Tracheomalacia is characterized by weakness of the tracheal wall resulting in dynamic airway collapse during respiration; severe cases often require surgical intervention. Off-label external splinting with degradable implants has been reported in humans; however, there remains a need to develop splints with tunable mechanical properties and degradation profiles for the pediatric population. The objective of this pilot study is to assess the safety and efficacy of silk fibroin-based splints in a clinically relevant preclinical model of tracheomalacia.

METHODS

Silk splints were evaluated in a surgically induced model of severe tracheomalacia in N = 3 New Zealand white rabbits for 17, 24, and 31 days. An image-based assay was developed to quantify the dynamic change in airway area during spontaneous respiration, and histopathology was used to study the surrounding tissue response.

RESULTS

The average change in area in the native trachea was 23% during spontaneous respiration; surgically induced tracheomalacia resulted in a significant increase to 86% (P < 0.001). The average change in airway area after splint placement was reduced at all terminal time points (17, 24, and 31 days postimplantation), indicating a clinical improvement, and was not statistically different than the native trachea. Histopathology showed a localized inflammatory reaction characterized by neutrophils, eosinophils, and mononuclear cells, with early signs suggestive of fibrosis at the splint and tissue interface.

CONCLUSION

This pilot study indicates that silk fibroin splints are well tolerated and efficacious in a rabbit model of severe tracheomalacia, with marked reduction in airway collapse following implantation and good tolerability over the studied time course.

LEVEL OF EVIDENCE

NA Laryngoscope, 129:2189-2194, 2019.

Three dimensional printing: A review on the utility within medicine and otolaryngology

Three dimensional (3D) printing is a novel technique that has evolved over the past 35 years and has the potential to revolutionize the field of medicine with its inherent advantages of customizability and the ability to create complex shapes with precision. It has been used extensively within the fields of orthopedics, dentistry, and craniofacial reconstruction with wide ranging utility including, medical modeling, surgical planning and the production of custom plates, screws and surgical guides. Furthermore, it has been used for similar means in the field of Otorhinolaryngology and also has potential to revolutionize the treatment of airway malacia. In fact, 3D printed external tracheal splints have already been studied in several pediatric patients with very promising results. The emerging field of 3D bioprinting, which integrates tissue engineering with 3D printing, may produce a paradigm shift with the potential introduction of customized functional biologic replacements.

Polymeric implant materials for the reconstruction of tracheal and pharyngeal mucosal defects in head and neck surgery

The existing therapeutical options for the tracheal and pharyngeal reconstruction by use of implant materials are described. Inspite of a multitude of options and the availability of very different materials none of these methods applied for tracheal reconstruction were successfully introduced into the clinical routine. Essential problems are insufficiencies of anastomoses, stenoses, lack of mucociliary clearance and vascularisation. The advances in Tissue Engineering (TE) offer new therapeutical options also in the field of the reconstructive surgery of the trachea. In pharyngeal reconstruction far reaching developments cannot be recognized at the moment which would allow to give a prognosis of their success in clinical application. A new polymeric implant material consisting of multiblock copolymers was applied in our own work which was regarded as a promising material for the reconstruction of the upper aerodigestive tract (ADT) due to its physicochemical characteristics. In order to test this material for applications in the ADT under extreme chemical, enzymatical, bacterial and mechanical conditions we applied it for the reconstruction of a complete defect of the gastric wall in an animal model. In none of the animals tested either gastrointestinal complications or negative systemic events occurred, however, there was a multilayered regeneration of the gastric wall implying a regular structured mucosa.

In future the advanced stem cell technology will allow further progress in the reconstruction of different kind of tissues also in the field of head and neck surgery following the principles of Tissue Engineering.

Biodegradable external tracheal stents and their use in a rabbit tracheal reconstruction model

OBJECTIVES/HYPOTHESIS

To design and develop an external biodegradable tracheal stent for use in airway reconstructive surgery.

STUDY DESIGN

Experimental model.

METHODS

Biodegradable external tracheal stents were fabricated from polyglycolic acid and poly(D,L-lactide-co-glycolide) (85:15). In vitro studies were performed to analyze the mechanical properties and degradative characteristics of these stents. Then the stents were tested in vivo in an anterior tracheal reconstruction model in New Zealand white rabbits.

RESULTS

The average dry modulus for the external stents was 1,800 kilopascal (kPa). All of the external stents cracked by 4 weeks in buffer solution. Significant mass loss was not appreciated until after 10 weeks in solution, but by 20 weeks the stents were nearly 100% degraded. In the in vivo portion of the study, the attrition rate for the control group was 23.1% versus 50% for the external stent group. The stridor rate was approximately 38% for both groups Of the rabbits that survived the entire 3 months of the study, the stented group, when measured by a balloon catheter method, had more patent airways than the control group, with an average stenosis of 27.8% versus 47.2%, respectively (P < .05). However, more accurate postmortem cast measurements of the internal airways did not confirm this.

CONCLUSIONS

The external biodegradable tracheal stent employed in this study degraded in a predictable fashion and may provide a new method to augment surgical reconstruction of the anterior tracheal wall.

The effects of resorbable plates on rabbit ear cartilage

BACKGROUND

When performing septorhinoplasty, deviated segments of septal cartilage can be straightened using cartilage or bone as splinting grafts. In some cases, autologous material is not available without an additional surgical procedure to harvest cartilage or bone. It is possible that resorbable plates can be used to splint and straighten deviated cartilage. Experience using bioresorbable rigid fixation devices on cartilage has been limited.

OBJECTIVE

To examine early histopathologic changes of rabbit ear cartilage and adjacent soft tissue following implantation with bioresorbable plates.

DESIGN

Nonrandomized, placebo-controlled trial.

SUBJECTS

Twelve adult New Zealand white rabbits.

MATERIALS AND METHODS

Ten adult New Zealand white rabbits (20 ears) underwent stenting of intact ear cartilage with LactoSorb plates (Lorenz, Jacksonville, Fla). Rabbits were killed 28 days after implantation, and the soft tissue, plates, and cartilage were harvested and prepared for histological examination. As controls, 2 rabbits (4 ears) underwent dissection and closure without stenting.

RESULTS

Six rabbits experienced superficial skin breakdown on the ventral surface of the ear caused by excessive wound tension of the implant. The cartilage-plate interface and the surrounding soft tissues stenting the dorsal side of the ear remained free of inflammation or necrosis for all animals. Simple elevation of the perichondrium revealed no differences in the appearance of the cartilage between the control and test rabbits.

CONCLUSIONS

Resorbable plates have no deleterious effects on cartilage during the first month of implantation. While short-term studies have documented the safety and efficacy of using bioresorbable plates, further studies are recommended.

Histopathology of laryngeal changes after long-term chondrosynthesis

Two patients treated for laryngeal tumors at the University of Lübeck are presented. Both underwent laryngeal reconstructions with plate and screw fixation systems immediately following partial laryngectomies. Recurrent disease was found at 14 and 55 months, respectively, and was subsequently managed by total laryngectomy. The laryngectomy specimens with the plate and screws in situ were evaluated histopathologically, paying special attention to the reaction of local tissue to the implants. Findings showed that the metallic plates were fixed with screws in the bony trabeculae of the laryngeal skeleton. The histological response showed primary wound healing without evidence of sequestration or implant loosening, as often associated with excess mechanical stress. Furthermore, there were no signs of tissue necrosis or widespread chronic inflammation. In both patients, a small discrete area of chronic inflammation and soft tissue fibrosis was noted adjacent to the screw heads. This study supports our previously documented clinical experience that the use of chondrosynthetic techniques is almost complication-free and is an ideal system for performing precise anatomical reconstruction of the laryngeal skeleton.

Resorbable fixation plates in head and neck surgery

A skeletal fixation system employing plates made of polylactic and polyglycolic acid has been employed at Indiana University Medical Center since July 1993 in 105 craniofacial reconstructions, 45 cases of maxillofacial trauma, 10 craniotomy flap repairs, and five cases involving reconstruction of the laryngotrachea. Because these plates eventually resorb, they offer significant theoretical advantages. No inhibition of structural growth should occur when using this system in children. Tissue tolerance of these plates has been excellent. The technical details of using heat to allow reshaping of the plates as well as the methods of fixation of the plates are discussed.